GB2026864A - Germicidal agents - Google Patents

Abstract

A composition of use for treating bacteria, yeasts, fungi, algae and slime formers, comprises in aqueous solution about 10-30% trihydroxymethyl- nitromethane and about 0.1-5% 2- methyl-3-oxo-5-chlorothiazoline-1,2. The compositions may be used for treating liquids, suspensions, dispersions or solids, eg. mineral-oil containing cooling lubricants, adhesives, glues, synthetic resin dispersions, paints, and in the pulp and paper industry, or may be used for disinfecting a locus. The compositions exhibit synergium and improved skin tolerance.

Description

SPECIFICATION Germicidal agents The invention relates to germicidal agents which can be used for example as preservative agents or disinfectants, especially for industrial applications.

It is currently a frequent requirement even in the industrial domain to treat certain products or process materials with preservatives in orde to guard against loss in value, deterioration etc caused by bacteria, yeast cells, or fungi. For example, it is thus an absolute requirement to protect industrial recycle waters against microorganisms and algae and, in the paper industry, to prevent an infestation of the pulp by slime-forming bacteria, fungi or yeast species.

By way of industrial preservatives there are employed a great number of compounds of very diverse structure and having a bactericidal and/orfungicidal action. Since the compounds used frequently differ in their effectiveness against different types of germs, combinations of various substances are often used.

In addition, from the point of view of practical applicability, a good solubility in water or polar solvents, thermal stability and a relatively high inertness to ionic compounds are important requirements. To this must be added the requirement that such agents must not have a high toxicity to warm-blooded species and must have good local tolerance in order to exclude the possibility of cutaneous reactions in the user. The above listed requirements already will suggest that no single preservative can satisfy the majority of them.

With the known preservatives, difficulties arise on one hand in their use owing to their toxicity or aggressivity, or, on the other hand, it is found that their effectiveness differs in degree against various bacteria or fungi, so that although a long-lasting preservation can be achieved in respect of certain germs, the activity against others remains inadequate.

The fundamental object of the invention is to develop a novel germicidal agent suited for industrial applicaton.

The present invention provides a germicidal agent comprising in aqueous solution about 10 - 30% trihydroxymethyl-nitromethane and about 0.1 - 5% 2-methyl-3-oxo-5-chlorothiazoline-1 ,2.

The germicidal activity of the compounds employed according to the invention has been known for some time. Trihydroxymethyl-nitromethane has been in use for some ten years to a limited extent as a disinfectant or preservative, and displays a significant though not particularly intensive activity against various bacterial strains. 2-methyl-3-oxo-5-chloro-thiazoline-l ,2, otherwise known as 5-chloro-2-methyl-3-oxo-1 ,2-thiazoline, has also been marketed in recent years by the firm Roehm and Hass, of Philadelphia, under the Trade Name of "Kathon 886" and recommended for use as an anti-bacterial, germicidal compound.

The aqueous solution marketed under the Trade Name "Kathon 886" contains approximately 14% of a mixture consisting of 2-methyl-3-oxo-5-chlorothiazoline-1,2 and of the unchlorinated compound, i.e.

2-methyl-3-oxo-thiazoline-1,2, in which the chlorinated compound predominates to a large extent. This aqueous solution further contains one mol magnesium chloride and one mol of magnesium nitrate as stabiliser, per mol of heterocyclic parent compound present before chlorination.

However, in aqueous solution and even in the highly diluted state 2-methyl-3-oxo-5-chlorothiazoline-l ,2 is so aggresive that owing to its highly damaging effect on the skin, to the extent that a single drop of a highly dilute solution is enough to cause blistering and long-lasting, painful skin irritation, it has found but little practical use as preservative agent in industrial applications.

It has now been surprisingly found that germicidal agents according to the invention with the two known compounds display a notable synergistic effectiveness, and that moreover the local tolerance to the agents is improved to such as extent that little skin irritation occurs. The synegistic effectiveness is shown clearly by the bactericidal and fungicidal activity which is substantially increased by comparison with the individual compounds. That the present agents do not exhibit strong skin-irritant properties is particularly surprising in view of the presence of the highly aggressive 2-methyl-3-oxo-5-chlorothiazoline-1,2.

The agents according to the invention can be used in numerous industrial fields of application. They have proved to be particularly suitable for the preservation of mineral-oil containing, semi or fully-synthetic aqueous cooling lubricant compositions, especially for use in the aluminium-working industry, for example in aluminium rolling mills. The agents according to the invention are also useful for preserving suspensions and dispersions, for example of adhesives, glues, synthetic resin dispersions and paint compositions. The concentration usually employed is of the order of 0.01 - 1.0%; only in cases of extreme requirements with high product sensitivity does the dosage have to be increased.

A further field of application is constituted by the protection of industrial recycle waters against microorganisms and algae. Here, the operating concentration is again in the range of 0.01 - 0.03% as a rule.

Another important field of application for the agents according to the invention is to be found in the paper and pulp industry, where in the preservation of brushing-on colours an addition of 0.02 - 0.05% is required to prevent viscosity variations. Moreover, the agents according to the invention can be very successfully used for slime suppression in the manufacture of paper and pulp. The slime formation, which subsequently leads to paper break on the rollers and must therefore be avoided above anything else, is mostly caused by aerobic and anaerobic bacteria, fungi, yeasts and by specific slime-forming atents. Such a slime formation can be reliably prevented by the addition of 10-250 ppm of an agent according to the invention to the stock suspension.

The invention will be illustrated with reference to the following examples.

Example 1 Preparation of the Solution 20 kg trihydroxymethyl-nitromethane were dissolved with slight warming in 50 kg distilled water. The solution was then admixed with 12 kg of a commercially available 14% aqueous solution of 2-methyl-3-oxo5-chlorothiazline, with the addition of 1 mol magnesium chloride and 1 mol magnesium nitrate per mol of the originally present parent heterocyclic compound. The solution was then made up to 100 kg weight with distilled water, such that it contained 20% trihydroxymethyl-nitromethane and 1.7% 2-methyl-3-oxo-5chlorothiazoline-1,2. The odour of the solution was neutral and mild, but it could be scented if desired by the addition of commercially available fragrance mixtures.

Example 2 Local Tolerance Test To evaluate local tolerance, the agent of Example 1 was tested on rabbit skin. 12 experimental animals, 6 males and 6 females, with an initial weight of between 2.3 and 2.8 kg were used.

The patch-test method was applied for testing for primary irritating properties. To this end, 0.5 ml of the substance to be tested was deposited on a piece of linen measuring 2.5 x 2.5 cm, covered with a plastic foil of the same size and made fast by means of a gummed bandage between the fore and rear extremities of the shaved back skin of the animals. Two groups were formed, in that in 6 animals the substance-impregnated cloth was applied to normal, uninjured skin, whilst in the other 6 animals the skin was scarified prior to the application.

At the end of a 24-hour exposure period the bandage was removed, and the skin examined. After a further 48 hours, i.e. after 72 hours following the application, the skin was again examined; the controls could be repeated daily until the end of the 14-day control period.

No changes could be observed after a single application of 0.5 ml ofthe disinfectant according to the invention on either the intact or on the scarified dorsal rabbit skin. Neither erythema nor swellings could be observed. There were no observable abnormalities in hair growth, nor any symptoms of systemic intolerance. Behaviour, general condition, pelt grooming, fodder consumption and body weight developmentwere all normal.

Example 3 Germicidal Activity in Suspension Tests In accordance with conventional procedures the germicidal activity of the germicidal agent embodying the invention was examined and gave the following results: Examination of Germicidal Activity in Suspension Tests Test organism % 4 hrs iday 2 days 3 days Yeast, type 28b 0.01 + + (+) 0.02 + - - 0.03 (+) - - - 0.05 (+) - - - 0.075 (+) - - - 0.1 - - - - Pseudomonas 0.01 + + - - 0.02 + + - 0.03 + - - - 0.05 + - - - 0.075 + - - - 0.1 + Asperglllus 0.01 (+) + + 0.02 (+) + 0.03 - - - 0.05 - - - 0.075 - - - 0.1 - - Mucor 0.01 + + - 0.02 + - - 0.03 + - 0.05 + - 0.075 (+) - 0.1 + - - = Test organism destroyed + = Growth, no destruction (+) = Isolated colonies

Claims (5)

1. A germicidal agent comprising in aqueous solution about 10 - 30% trihydroxymethyl-nitromethane and about 0.1 - 5% 2-methyl-3-oxo-5-chlorothiazoline-1 2.

2. An agent according to Claim 1, comprising about 20% trihydroxymethyl-nitromethane and about 1.7% 2-methyl-3-oxo-5-chlorothiazoline-1 ine-1,2.

3. An agent according to Claim 1 or 2 which contains a small quantity of 2-methyl-3-oxo-thiazoline-1 ,2.

4. A process for preserving a liquid, emulsion or solid which comprises incorporating a germicidal agent according to any of Claims 1 to 3.

5. A process for disinfecting a locus which comprises applying a germicidal agent according to any of Claims 1 to 3.